Coaxial dial locking device



June 30, 1953 R. M. SIGMON, JR

COAXIAL DIAL LOCKING DEVICE Filed 001;. 6, 1950 INVENTOR. gy edz':

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Patented June 30, 1953 SOAXIAL DIAL LOCKING DEVLGE Ross M. Sigmon, J12,Winston-Salem, N. 0., assignor to Western Electric Company,Incorporated, New York, N. 1 a corporation of New York applicationQctobcr 6, 19.50, Serial No. 188,311

5 Claims.

This invention relates to locking devices for adjustabl controls andmore particularly to a device for locking the indicating dial of arotatable control in any desired position about its axis of rotation.

In various types of instruments, it is often desirable to accuratelyadjust the tension or friction on the control knobs of the instrumentfrom the outside or front panel and to make this ad.- justment in asimple and rapid manner. Furthermore, after th adjustment has been made,the knobs and controls should be of such construction that they can beeasily changed without resort to a special tool for releasing the tension or friction.

In a large number of instruments, the indicat in dial is secured to androtates with the knob or control and it is desirable to lock the dial ofthis type of instrument without the use of a disw ich would produceinaccuracies in the dial setting. I

Accordingly, one object of thi invention is to provide a locking devicewhich can be adjusted without the application of force to the outerextremity of the dial.

Another object is to provide a control knob which may be accuratelyadjusted and to provide proper tension or friction for readily lockingthe control in an adjusted position.

Another object of the invention is to provide a locking assembly foreffecting fine adjustment of the friction on the control knob and tohave the locking means so constructed that a special tool is not neededto obtain the adjustment.

With these and other objects in view, the in- I vention comprises acontrol knob secured to an indicating dial which is mounted on a shaftfor rotating 2,. control member. Th control knob is internally threadedto receivc a loglghclt while when turned in one direction'ihoves forwardto force a slidabls engaging assembly into contact with a stationaryfriction plate. The tension on the dial and hence on the control shaftis thus increased until the dial is locked in position. When the lockbolt is turned in the opposite direction, the contact plate of theengaging assembly is separated from the fixed friction plat and thetension on the dial is released. The dial and the control shaft may thenbe rotated to any desired position by turning the control knob.

ther objects and advantages will be apparent from the following detaileddescription when considered in conjunction with the accompanyingdrawings, wherein ting force on the outer extremity of the dial Fig. 1is a front elevational view of an indicating dial and the locking deviceembodying the invention;

Fig. 2 is an enlarged cross-sectional view taken along line 2-2 of Fig.1 showing the indicating dial, its control knob and the lockingassembly; and

Fig. 3 is a sectional view taken along line 3-3 of Fig. 2.

Referring now to the drawings, wherein like referenc numerals indicatethe same elements throughout the several views, attention is firstdirected to Fig. 2 wherein the reference numeral 10 designates anindicating dial on which is securely mounted a control knob I l. Thedial ill is also attached to a bushing it which is secured to a shaft l9to rotate a control member 23. The control knob H has a central openingwhich is internally threaded to receive a rotatable look bolt i2, theouter end of which protrudes beyond the front face of the control knob.Clockwise rotation of the lock bolt I2 moves a frictional engagingassembly, indicated generally as it, to the right as viewed in Fig. 2 tocompress a resilient member '24 which is inserted between a block Id ofthe assembly l3 and the dial it to force the assembly I3 to the leftwhen the bolt i2 is rotated counterclockwise to unlock the dial.-

This frictional engaging assembly l3 consists of a block M, a pluralityof pins it: drive fitted into the block and securing in spaced relationthereto a holding plate I6, and a facing ll of friction material securedto th holding plate. The block it and the holding plate iii are tionedand spaced on opposite sides of the indicating dial it. The securingpins 55 sliclably extend through aperture 22 in the dial andpositionthellock M with respect to the holding plate TG so that thesliding movement of the engaging assembly i3 is limited by thepredetermined fixed spacing between the block Hi and the plate it. Anysuitable friction material may be used for the facing I'l, however,experiments have shown that corprene, a synthetic rubber made fromground cork and rubber derivatives, is an excellent facing material.

The forward movement of the reciprocable assembly I 3 forces the facingll into engagement with a fixed knurled fibre friction plate 2% securedto a stationary panel 2|. Frictional contact between the stationaryfriction plate 2t and the facing ll prevents rotation of th control knobII and indicating dial l0 and hence locks the dial Ill in any desiredposition.

From the foregoing detailed description,. it is believed that thegeneral operation of the appaposi ratus may be readily understood. Theindicating dial I is rotated to a desired position by means of controlknob H to move the shaft 19 and the control mechanism 23 attachedthereto to a predetermined position. To look the dial and th controls 23actuated thereby in the desired posi tion, the control knob H is heldfirmly in one hand while the lock bolt I2 is threaded into the controlknob with the other hand to compress the spring 2:3 and move theassembly l3 forward or to the right as viewed in Fig. 2. The slidableengaging assembly 13 is thus moved forward until the facing 5? contactsthe stationary friction plate 20. Frictional engagement between thefacing and the friction plate locks the dial H) and the actuatedmechanism in position.

To release the locking device, the control knob II is held in one handwhile the lock bolt i2 is manually threaded out of the control knob torelease the assembly 13. The compression spring 24 then forces theassembly 13 and its friction facing I1 away from the stationary frictionplate 28. The dial Iii is free to be rotated to any desired position.

Thus the indicating dial it may be rapidly locked and released in anydesired position without using a special tool and without using adistorting force on the dial.

It is to be understood that the above described arrangements are merelyillustrative of the appli cation of the principles of the invention, andnumerous other arrangements may be readily devised by those skilled inthe art which will embody the principles of the invention and fallwithin the spirit and scope thereof.

What is claimed is:

l. A device for looking a dial, comprising a hol low control knobsecured to the dial, a stationary friction plate, a movable frictionplate slidably connected to the dial and mounted parallel to thestationary plate, and means concentrically movable in the hollow of saidcontrol knob to actuate the movable friction plate parallelly toward thestationary friction plate to cause full area contact therebetween tolock the dial against movement.

2. In a device for looking a rotatable hollow control knob after it isset at a predetermined position, a stationary flat friction plate, amovable flat friction plate, a lock bolt threaded in the hollow of saidcontrol knob to move said movable fiat friction plate parallelly intoplane contact with said stationary flat friction plate to preventrotation of the control knob, means connected to thesaidlnqable fiatfriction plate and to prevent rotation of saiirmogble flat frictionplate relative to said control knobyandgresilient means for normallyholding the movable fiat friction plate away from the stationary flatfriction plate in unlocked position.

3. A mechanism for locking dials comprising a hollow, internallythreaded control knob secured to a dial; a member threaded into thehollow of and coaxial with said control knob and having one endprotruding beyond the control knob; a stationary flat friction plate; amovable flat friction plate; and means frictionally securing saidmovable flat friction plate to the other end of said threaded member formoving the said movable plate into contact with said stationary flatfriction plate to lock the dial in a predetermined position when saidmember moves forward in the hollow of the control knob.

4. In a device for locking rotatable dials, a hollow internally threadedcontrol knob secured to the dial; a stationary friction plate; aslidable engaging means including a block, spacing members and a holdingplate, the sliding movement of said engaging means being limited by thespacing between the block and the holding plate; and a member threadedinto the hollow of said control knob to force the engaging means intoengagement with said friction plate to lock the dial in position, saidmember being threaded out of the hollow of said control knob to releasethe dial.

5. In a device for looking a member in any desired rotative position; ashaft for rotating said member; an indicating means secured to the shaftand rotatable therewith; means for rotating the indicating means, theshaft and the said member to a desired position; a stationary frictionplate positioned about said shaft; and slidable engaging means movableinto engagement with said stationary friction plate to lock theindicator, the shaft and the said member in the desired selectedposition; said slidable engaging means including a movable frictionplate mounted parallel to the stationary plate and positioned betweenthe indicating means and the stationary friction plate, pins secured atone end to the movable friction plate and having their opposite endsextending through the indicating means to prevent relative rotationbetween the movable friction plate and the indicating means, butpermitting sliding movement therebetween, a block secured to the ends ofthe pins that extend through the indicating means, means adjacent saidblock and slid able with respect to the indicator and the rotating meansfor moving the block, pins, and plate so that the movable friction platewill be forced into locking engagement with the said stationary frictionplate.

ROSS M. SIGMQN, JR.

References Cited in the file of this patent UNITED STATES PATENTS NumberName

